Nashville Airport Cuts Power Use In Half By Harnessing Quarry’s Cold Water

The geothermal system was built by Energy Systems Group on an expedited timeline.

courtesy Nashville International Airport

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A geothermal system at the Nashville International Airport is saving even more money than originally projected.

At a ceremonial opening Tuesday, airport officials announced the eco-friendly air conditioner is already on track to save $430,000 a year on utility costs. Still, it will take a while to recoup the $10 million price tag, though some of that was paid for by government grants.

The closed system, which has been in use since February, pipes chilled water to the terminals to help cool the air. The water is then pumped back, where it’s cooled again by passing through the deep quarry water, which is a steady 50 degrees year-round. In a way, the cycle functions almost like a car radiator.

The system is the largest of its kind in the U.S., according to airport officials.

“The Airport Authority is committed to making sustainability an integral part of our business model," CEO Rob Wigington said in a statement. "Not because sustainability is easy — rather, it is often a complex process — but because the benefits to our airports, the region and our environment are overwhelmingly positive.

Environmentalists have officially dropped their lawsuit against the city of Franklin over contamination of the Harpeth River. An out-of-court settlement appeared to be in the works in March, though neither side would comment at the time.

The fight over a quarry in Old Hickory has now zeroed in on a single state permit. The prospective mine operators, Industrial Land Developers LLC, have presented a plan to keep nearby waterways clean while they dig for rock.

But opponents used a public hearing Monday to lob questions at the inspectors who get final say over the permit.